Integrated circuits are usually fabricated on a semiconductor wafer. During the manufacturing process, a stepper machine is used to move the processing arm to print images, i.e. dies, on a wafer. The pattern on the photomask (also called a reticle) is exposed repeatedly side by side on the surface of the wafer. Multiple dies are usually formed on the surface of a single wafer. Depending on the size of the die, in some cases, multiple die patterns can be included on a single reticle to reduce the cost for the reticle set.
Multiple layers of these reticle images make up a device. Normally, each different layer will be formed by a different reticle, and as the number of layers in a device increases with each technology node, the mask set cost to produce a device increases. Furthermore, in order to produce a different device, e.g., a device of a different size or a device with more resources, a new reticle set would normally be required, further increasing the mask cost. In order to reduce the cost of a device, the number of masks required to produce a single device needs to be reduced. The cost of the device can then be lowered by maximizing the reusability of a single mask set and a more cost effective solution can be achieved by sharing mask sets for multiple devices.
It would therefore be advantageous if a single mask set can be used to handle a variety of design sizes with varying resources. In other words, the same mask set can be used to create a number of different devices with different configurations.